Floor material for sports

Abstract

To provide a floor material for sports activities having a constant FR value regardless of manufacturing conditions and / or construction conditions for the purpose of obtaining a highly efficient surface.SOLUTION: A floor material for sports includes a tread layer (2) including at least one layer of an elastomer material and a support layer (3) including at least one layer of an elastomer material, wherein the support layer (3) includes a first arrangement of voids having an elliptical cross section (5).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Forming the subject of the present disclosure is sports flooring, for example used to make athletics tracks. [Background technology]

[0002] Documents such as EP-0913524, EP-1096080 or EP-2055833 filed in the name of the present applicant describe sports flooring comprising a treading layer made of an elastomer and a support layer also made of an elastomer, the support layer having, on its underside, i.e. the side opposite the treading layer, support ribs of various nature.

[0003] Flooring of the above-identified types has been widely used for many years in buildings for sports activities such as playing fields, athletic fields and gymnasiums.

[0004] The flooring material is manufactured by starting with an elastomer mixture and then, for example, through one or more of the following operations: mixing, extrusion, and cascade calendering. In this way, a generally wavy pattern can be imparted to the upper surface of the treading layer, with irregularities that primarily perform the anti-slip function on the upper surface and the shock-absorbing function on the lower surface.

[0005] In the solution described in document EP-0913524, the underside of the flooring is provided with transverse ribs inclined relative to the treading layer, which are connected together by longitudinal ribs that substantially resemble bridges connecting adjacent transverse ribs.By using a non-uniform mesh containing two different types of ribs, it is possible to produce flooring that exhibits different compliance (usually understood in the sense of elastic type resilience) properties according to the running direction of the flooring.

[0006] Also, in the solution described in document EP-1096080, the support layer includes ribs that are inclined relative to the treading layer. These inclined ribs are arranged in pairs and cooperate to form suction cup fastening structures for the floor covering. These inclined ribs contribute to a small extent to the elastic compliance characteristics as a whole and therefore to the support function for the floor covering. Instead, this function is mainly left to other ribs that extend in a direction that is essentially longitudinal relative to the treading layer.

[0007] When it comes to sports flooring for running, the terms "transverse" and "longitudinal" are intended to refer to the running direction on the flooring. Insofar as the flooring in question is usually produced in the form of rolled sheets, the running direction can be specified in a specific way. The sheets are laid out one after the other on the floor in a "longitudinal" direction (i.e. in the direction of length or extension), the longitudinal direction of the sheets extending exactly in the running direction. This direction also usually corresponds to the direction of the calendering process.

[0008] The solution that constitutes the specific subject of documents EP-0913524 and EP-1096080 is therefore characterized in that the voids (or cavities) provided on the underside of the support layer are delimited by ribs that constitute a heterogeneous (or non-uniform) mesh with different properties that comply with different functions (supporting ribs / fixing ribs) and / or standards.

[0009] Over the years, instruments and procedures have been developed that allow the properties of the above-mentioned types of flooring to be determined accurately and quantitatively. Standard EN 14877 defines the methods and parameters and specifies floor surfaces for outdoor sports facilities. Standard EN 14904 regulates and deals with indoor multi-sport floor surfaces.

[0010] In particular, standard EN 14808 allows the specification of a parameter, namely the "force reduction" (FR), which essentially corresponds to the characteristic behavior of a floor covering, expressed as a percentage, when a weight of standard dimensions is dropped on the floor, compared to the behavior of a hard surface subjected to a similar stress.

[0011] Flooring designed for use in sports activities has an FR value in the range of 25% to 50%, in particular athletics tracks according to standard EN 14877 have FR values ​​in the range of 25% to 34% or 35% to 50%, and athletics tracks complying with the rules of the International Association of Athletics Federations (IAAF) for high-level competitions have values ​​of 35% to 50%.

[0012] With respect to stress from walking or running, the upper limit corresponds to flooring that can be characterized as "softer" and the lower limit corresponds to flooring that can be characterized as "harder."

[0013] Athlete safety and protection from injury during training and competition are particularly important with regard to the requirements for flooring surfaces for sports activities. For example, World Athletics regulations recommend that synthetic flooring surfaces for training facilities should generally have higher impact absorption than those for competition facilities. Flooring surfaces are characterized by other technical characteristics, such as abrasion, hardness, ultimate strength, and relative elongation at break and tear strength, which make it possible to describe the surface's resistance to the wear phenomena of the track and the stresses exerted by the spikes on the athletes' shoes.

[0014] The overall quality of an athletic flooring surface, understood as the optimal interaction between the athlete and the surface, is determined by the combination of all these characteristics. The mode of interaction can vary depending on the sporting activity being performed as well as the running style of each individual athlete. The interaction of the athlete's foot with the track on which the athlete runs implies not only a longitudinal movement, i.e., in the running direction, but also a lateral "roll" movement, which corresponds to a kind of rotational movement of the sole of the foot from the fifth metatarsal to the first metatarsal in a vertical plane perpendicular to the running direction.

[0015] Additionally, while "soft" surfaces may be perceived by some athletes as a "resting" surface, softness should not be understood to be a disadvantage to athletes, for example, in terms of explosive power (burst). Instead, such an understanding privileges hard tracks, since there is no direct correlation between FR values ​​and the transfer of propulsive forces exerted by athletes on the ground within the range of values ​​allowed by the standard. Instead, uniformity of behavior on athletics tracks has proven particularly important, as a lack of surface uniformity forces athletes to modify their athletic movements, resulting in reduced efficiency.

[0016] Document EP 2055833 discloses a flooring of the aforementioned type, in which the support layer has a series of voids separated by ribs, which form a mesh of ribs distributed according to a uniform pattern. The voids have an elongated shape, the main dimension (longitudinal dimension) of the voids being aligned with the running direction of the flooring. In one embodiment, the voids occupy a volume equal to at least 28-30% of the volume of the support layer, which indicates that the flooring is rather "soft." The elongated shape of each void (e.g., consisting of an irregular hexagon or diamond in plan view) is oriented such that its main dimension is aligned with the running direction on the flooring, meaning that the aforementioned softness is present primarily in a direction perpendicular to the running direction, thus facilitating the aforementioned rolling movement in an athlete-acceptable manner without negating the desired property of greater stiffness, which consequently favors the athlete's explosive power in the running direction. The solution described in EP 2055833 uses a flooring material whose support layer has a uniform ribbed mesh, making it possible to obtain better performance results than those achieved with flooring materials commonly employed in the past (which typically have rectangular shaped gaps).

[0017] However, at the same time, the above-mentioned flooring materials can have the drawback that the FR value changes when, for example, the volume of voids present in the support layer changes. This situation can occur, for example, during the installation of such flooring materials. The adhesives typically used to attach flooring materials to surfaces can fill some of the voids, resulting in sometimes unpredictable changes in the FR value.

[0018] With the aim of obtaining highly efficient surfaces for sports activities with a performance level higher than that of known flooring materials, improved solutions that make it possible to produce flooring materials whose FR values ​​are constant regardless of the manufacturing and / or application conditions are currently of great interest.

[0019] [Objectives and Overview] It is an object of one or more aspects of the present disclosure to provide a sports flooring that includes structural features that can overcome the above-mentioned drawbacks.

[0020] According to one or more aspects, the above-mentioned object is achieved by a floor covering having the characteristics set out in the resulting claims, which are to be understood as forming an integral part of this description.

[0021] Aspects of the present disclosure provide a sports flooring including a treading layer, the sports flooring including at least one layer of elastomeric material and a support layer, the support layer including at least one layer of elastomeric material, the support layer including a first array of voids having elliptical cross-sections. The present disclosure further provides an athletics track, particularly a running track, comprising a flooring according to aspects of the present disclosure. [Brief explanation of the drawings]

[0022] One or more aspects will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0023] [Figure 1] FIG. 1 is a perspective view of a portion according to an embodiment of the present disclosure. [Figure 2] FIG. 2 shows, on the left, a bottom view of a portion of a flooring according to an embodiment of the present disclosure, and, on the right, a cross-sectional view of a flooring according to an embodiment of the present disclosure. [Figure 3] FIG. 3 shows a pressure roller that can be used to obtain the support layer of the flooring described. [Figure 4] Figure 4 shows, on the left, the structure of the FEM model of the Berlin Artificial Athlete, a device for measuring FR (EN 14808), and, on the right, an example of a flooring material used in the experimental tests described in this application. [Figure 5] FIG. 5 shows the results of an FEM simulation showing the FR values ​​resulting from various conditions of voids in the lower layer of the flooring. [Figure 6] Figure 6 shows the results of FEM simulations showing the FR values ​​resulting from various values ​​of the void depth. [Figure 7]FIG. 7 shows the FR values ​​resulting from different void volumes when the overall thickness of the flooring is the same. [Figure 8] Figure 8 shows a comparison of the FR results obtained from flooring containing voids of different shapes. [Figure 9] FIG. 9 shows a comparison of the FR results obtained from flooring containing voids of different shapes, with the same flooring thickness and the same void depth.

[0024] [Detailed explanation] In the following specification, various specific details are set forth for the purpose of providing a thorough understanding of examples of aspects of the present disclosure. An aspect can be achieved without one or more of the specific details, or by using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not explained or described in detail to avoid obscuring various aspects of the aspects of the present disclosure.

[0025] References to "an embodiment" or "one embodiment" in this specification's structure are intended to indicate that the particular features, structures, or characteristics described in connection with that embodiment are included in at least one embodiment. Thus, terms such as "in an embodiment" or "in one embodiment" may appear in various places throughout this specification, but do not necessarily refer to one and the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0026] The reference signs used in this specification are used merely for convenience and do not therefore define the scope of protection or the scope of the embodiments.

[0027] FIG. 1 is a perspective view of a portion of a flooring 1, which includes a treading layer 2 (which faces upward when the flooring 1 is placed in a predetermined state) comprising a layer of elastomeric material, and a support layer 3 (which faces downward when the flooring 1 is placed in a predetermined state) comprising a layer of elastomeric material.

[0028] The two layers 2 and 3 can be connected together (typically during a process that results in the formation of the flooring 1) at a connection surface 4 (visible on the right side of Figure 2), which defines the interface between the two layers 2 and 3.

[0029] The treading layer may include an inner portion 2a of continuous structure that connects to the support layer 3 at a location corresponding to the connecting surface 4, and an outer portion opposite the support layer 3, this outer portion exhibiting a surface pattern that results in protrusions 6 extending between a bottom surface B corresponding to the interface with the inner portion 2a and a top surface T. In one embodiment, the height or protrusion of the protrusions 6, i.e., the distance between the bottom surface B and the top surface T (this distance is designated by S2 on the right side of Figure 2), is equal to at least 30%, preferably approximately 33%, of the thickness S1 of the treading layer 2 measured between the connecting surface 4 and the top surface T of the protrusions 6, as previously described.

[0030] The support layer 3 has a series of voids distributed through the layer of elastomeric material on the side opposite the treading layer 2, and therefore facing the underlayment onto which the flooring 1 is laid. The voids and protrusions correspond to the desired voids and protrusions and can be formed by providing a complementary pattern on the calendering rollers.

[0031] The voids are voids that open on the opposite side of the treading layer. They open precisely on the back side of the flooring 1 and are delimited (i.e. surrounded) by ribs 8, which have a uniform height and extend to form a regular mesh of ribs to support the flooring 1.

[0032] In particular, the flooring 1 comprises a support layer 3 comprising a layer of elastomeric material having a first arrangement with an elliptical cross section 5 .

[0033] From the bottom view (left side) of Figure 2, it can be seen that the support layer comprises a first array of voids with an elliptical cross section 5 having a major axis A (major dimension, i.e., length) and a minor axis B (minor dimension, i.e., width).

[0034] The major axis A is oriented in the direction of the length Z of the flooring (ie the direction of travel) in the embodiment shown in Figure 2 (left side).

[0035] In one or more embodiments, the voids 5 of the first array of voids may exhibit a major axis A oriented perpendicular to the longitudinal direction Z of the flooring.

[0036] As already explained at the beginning of this specification, the direction indicated by the double arrow Z in Figures 1 and 2 can be specified in a specific way, insofar as the flooring referred to is usually produced in the form of rolled sheets. The sports flooring forming the subject of the present disclosure may be in the form of longitudinally rolled sheets. Many sheets are rolled up and unfold one after the other in the longitudinal direction (i.e., lengthwise), the longitudinal direction of each sheet extending exactly in the running direction. Furthermore, the direction Z usually corresponds to the direction in which the calendering process is carried out. Thus, the sports flooring may comprise a plurality of sheets of flooring having a longitudinal dimension (or dimensions), in which each sheet of the plurality of sheets of flooring is longitudinally aligned with each of the other sheets of flooring of the plurality of sheets of flooring.

[0037] In one or more embodiments, each void 5 in the first array of voids may further extend along a conical wall (or a wall tapering toward the treading layer 2) within the thickness of the support layer 3. Such a characteristic may result in minimal deformation of the wall after the removal from the mold step.

[0038] In one or more embodiments, the support layer 3 may further include a second array of voids distributed in the layer of elastomeric material having an elliptical cross-section 5a with a first axis a and a second axis b (which are perpendicular to and coplanar with the major axis A of the elliptical cross-section of the voids 5 of the first array of voids).

[0039] In one or more embodiments, the first axis a and the second axis b may have the same length.

[0040] In one or more embodiments, the voids 5 a of the second array of voids have an elliptical cross-section, where the first axis a and the second axis b have a length that is less than the major axis A of the cross-section of the voids 5 of the first array of voids.

[0041] In one or more embodiments, the first axis a and second axis b of the voids 5a of the second array of voids have a length that is less than the minor axis B of the cross section of the voids 5 of the first array of voids.

[0042] In one or more embodiments, each void 5a of the second array of voids can also extend along a conical wall (or a wall tapering toward the treading layer 2) within the thickness of the support layer 3. Such a characteristic can result in minimal deformation of the wall after the demolding step.

[0043] The voids 5 of the first array of voids may present an elliptical cross-section, the major axis A of which is between 6mm and 18mm, preferably between 9mm and 15mm, more preferably between 11mm and 15mm.

[0044] In one or more embodiments, the voids 5 of the first array of voids may exhibit an elliptical cross-section, the minor axis B of the elliptical cross-section being between 6 mm and 12 mm, preferably between 6 mm and 10 mm, and more preferably between 7 mm and 10 mm.

[0045] Preferably, the ratio of the length of the major axis A to the length of the minor axis B may be 1-3, preferably 1-2.

[0046] In one or more embodiments, the voids 5a of the second array of voids may exhibit an elliptical cross-section, with a first axis a of the elliptical cross-section being between 0 mm and 8 mm, preferably between 2 mm and 6 mm, and more preferably between 3 mm and 5 mm.

[0047] The voids 5a of the second array of voids may present an elliptical cross section, the second axis b of which is between 0mm and 8mm, preferably between 2mm and 6mm, more preferably between 3mm and 5mm.

[0048] Preferably, the ratio of the extension of the first axis a to the extension of the second axis b may be between 1 and 2, preferably between 1 and 1.2.

[0049] In one or more embodiments, the distance C between the centers of two consecutive voids of the first array of voids 5 (distance C oriented in the longitudinal direction Z of the track) may be 12 mm to 32 mm, preferably 12 mm to 27 mm, more preferably 14 mm to 26 mm.

[0050] In one or more embodiments, the distance D between the centers of two consecutive voids in the first array of voids 5 (distance D oriented in a direction perpendicular to the length Z of the flooring 1) may be 12 mm to 32 mm, preferably 15 mm to 24 mm, more preferably 17 mm to 21 mm.

[0051] The depths of the voids in the first array 5 and the second array 5a (extending within the thickness of the support layer 3) may be the same as or different from each other. In one or more embodiments, the depth of the voids 5 may be 2 mm to 15 mm, preferably 3 mm to 10 mm, and more preferably 3 mm to 6 mm.

[0052] In one or more embodiments, the depth of the voids 5a may be 2 mm to 15 mm, preferably 3 mm to 10 mm, and more preferably 3 mm to 6 mm.

[0053] The product of distance C and distance D (respectively the horizontal and vertical distance between the centres of two successive ellipses) identifies a cross section, which is repeated regularly on the surface and contains two major and two minor ellipses. This area is defined as the "sports surface unit element".

[0054] The unit element is 144 mm 2 ~1024mm 2 , preferably 180mm 2 ~648mm 2 , more preferably 238 mm 2 ~546mm 2 It may have a region where:

[0055] The flooring forming the subject of this disclosure is 2 and consequently may contain a number of unit elements between 976 and 6944, preferably between 1543 and 5555, more preferably between 1831 and 4201.

[0056] The flooring forming the subject of the present disclosure may comprise a first arrangement of voids 5 with an elliptical cross section, in which case the number of voids is between 1952 and 13888, preferably between 3086 and 11110, more preferably between 3662 and 8402 per square meter of flooring.

[0057] The flooring forming the subject of the present disclosure may further comprise a second array of voids 5a having an elliptical cross section with a first axis a and a second axis b, which are perpendicular to each other and coplanar with the major axis A, in which case the number of voids is between 1952 and 13888, preferably between 3086 and 11110, more preferably between 3662 and 8402 per square meter of flooring subject.

[0058] In one or more embodiments, the voids 5;5a of the flooring may occupy a volume equal to at least 12% of the volume of the support layer.

[0059] The support layer 3 may have a thickness of 3 mm to 15 mm, preferably 6.5 mm to 10 mm. The treading layer 2 may have a thickness of 3 mm to 9 mm, preferably 4 mm to 8 mm, more preferably 5 mm to 7.5 mm.

[0060] The total thickness of the flooring may be from 6mm to 18mm, preferably from 10.5mm to 16mm, and even more preferably from 13.5mm to 15mm.

[0061] The structure of the voids with elliptical cross section creates a uniform and homogeneous mesh of ribbing, with unit elements that are regularly repeated and that act as a support structure for the flooring as a whole and / or project perpendicularly to the treading layer to substantially the same extent.

[0062] Treading and Support Layer Composition Both the treading layer 2 and the support layer 3 comprise at least one layer of elastomeric material. The expression "at least one layer of elastomeric material" means at least one layer comprising at least one elastomer.

[0063] Treading layer configuration The treading layer 2 comprises at least one layer of elastomeric material, which may further comprise rubber powder and preferably at least one filler, preferably a mineral filler, which may further comprise at least one pigment.

[0064] In one or more embodiments, the at least one elastomer can be selected from the group consisting of synthetic rubbers such as, for example, styrene-butadiene rubber (SBR), ethylene-propylene-diene monomer (EPDM) rubber, natural rubber (NR), and mixtures thereof.

[0065] In one or more embodiments, the treading layer may comprise a polyurethane as an elastomer, preferably in combination with a synthetic rubber. Polyurethanes that may be used may be obtained, for example, by the reaction of a polyol with an isocyanate.

[0066] In one or more embodiments, blends based on NR, SBR, and EPDM may be preferred to obtain compositions with a pleasing aesthetic appearance and a good combination of ultimate tensile strength and relative elongation at break, as well as good resistance to aging and degradation by atmospheric agents.

[0067] In one or more embodiments, the support layer may include at least one elastomer in a content of 7 wt% to 50 wt% (% w / w) of the layer, preferably 20 wt% to 35 wt%.

[0068] In one or more embodiments, the at least one elastomer may include styrene-butadiene rubber (SBR) in a content of 5 wt% to 30 wt% of the layer, EPDM rubber in a content of 5 wt% or more, preferably 6 wt% to 15 wt% of the layer, and EPDM rubber and / or natural rubber (NR) in a content of 5 wt% or more, preferably 6 wt% to 15 wt% of the layer.

[0069] In one or more embodiments, the at least one filler contained in the composition may be selected from the group consisting of organic (wood flour, cellulose fibers) or other inorganic (mainly talcum, calcium carbonate, silica, carbon black, kaolin, aluminum trioxide, magnesium dioxide), and possibly biobased fillers. The at least one filler is present in an amount of 30 wt% to 200 wt%, preferably 30 wt% to 150 wt%, based on the weight of the at least one elastomer.

[0070] In one or more embodiments, the rubber crumb is preferably obtained by mechanical processing from a crosslinked elastomer mixture, selected from pre-consumer or post-consumer rubber manufacturing processes. The rubber crumb is preferably halogen-free and may have a particle size of 50 μm to 2 mm, preferably 400 μm to 1 mm. The rubber crumb may be in an amount of 30 wt% to 200 wt%, preferably 100 wt% to 150 wt%, based on the weight of the at least one elastomer.

[0071] In one or more embodiments, the treading layer may include at least one pigment that is inorganic (e.g., red iron oxide, yellow iron oxide, brown iron oxide, green chromium oxide, and titanium oxide, among others) or organic (e.g., monoazo-, diazo-, and phthalocyanine-based pigments, as well as quinacridone-, perylene-, perinone-based pigments, and diketo-pyrrolopyrrole-based pigments, among others, by way of example only). The pigment may be present in an amount of 0.3 wt % to 25 wt %, preferably 1 wt % to 20 wt %, based on the weight of the support layer.

[0072] In one or more embodiments, the treading layer composition may further include at least one compatibilizer in combination with at least one reinforcing filler to provide a treading layer that can impart resistance to impact, abrasion, and tear to the surface to which it is applied.

[0073] In one or more embodiments, the at least one compatibilizer may be selected from the group consisting of silanes, preferably mercaptosilanes and / or vinylsilanes, hydrocarbon-derived resins and / or waxes (e.g., benzofuran resins, coumarone resins, aliphatic hydrocarbon resins, commonly known as C5 resins, C9 resins, or C5 / C9 resins), long-chain fatty acids, preferably stearic acid and oleic acid, and mixtures thereof.

[0074] In one or more embodiments, the at least one compatibilizer may comprise a mixture of mercaptosilane, stearic acid, and coumarone.

[0075] The mixture offers the dual advantage of facilitating the incorporation of fillers and reducing the viscosity of the composition, thus making it easier to process, for example via calendering.

[0076] In one or more embodiments, the silane may be used in liquid form. If the manufacturing process of the support layer involves a step of sulfur crosslinking of the mixture, preferably mercaptosilanes may be used, while if the crosslinking step is carried out using peroxides, preferably vinylsilanes may be used.

[0077] In one or more embodiments, the treading layer composition may include mercaptosilane and / or vinylsilane in an amount of 0.1 wt% to 2 wt%, preferably 0.3 wt% to 1 wt% of the composition.

[0078] In one or more embodiments, the treading layer composition may include coumarone in an amount of from 1 wt% to 3 wt%, preferably from 1.5 wt% to 2.5 wt% of the composition.

[0079] In one or more embodiments, the treading layer composition may include a long chain fatty acid, preferably stearic acid, in an amount of 0.3 wt% to 2 wt%, preferably 0.5 wt% to 1 wt% of the composition.

[0080] In one or more embodiments, the treading layer composition may include chemical additives, also called process aids, that are useful in industrial plants to control the viscosity and workability of the composition.

[0081] In one or more embodiments, the processing aid may be, for example, a plasticizing compound, which allows for adjustment of the viscosity of the composition and can adjust the glass transition temperature of the elastomer, which changes after the crosslinking process of the composition. The plasticizing compound may be selected from the group consisting of phthalates, phosphates, adipates, sebacates, aliphatic and aromatic oils, antiozonants and dispersants, polyethylene glycol (PEG), fatty acid esters, metal soaps (e.g., calcium stearate and zinc stearate), zinc and stearic oxides, reinforcing resins, and adhesion promoters or inhibitors.

[0082] The crosslinking step of the composition used to obtain the treading layer may be carried out by vulcanization using a sulfur process and accelerators, or by vulcanization using sulfur donors, or by crosslinking using other peroxide crosslinking agents (for example dicumyl peroxide or tert-butyl peroxide), or by a combination of the three processes mentioned.

[0083] In one or more embodiments, the crosslinking accelerator may be selected from the group of, for example, CBS (cyclohexyl-benzothiazole sulfenamide, CAS No. 95-33-0), TMTD (tetramethylthiuram disulfide, CAS No. 137-26-8) or MTB (mercaptobenzothiazole, CAS No. 149-30-4), ZDBC (zinc dibutyldithiocarbamate, CAS No. 136-23-2), or other accelerators of the same series (sulfenamides, thiurams, thiazoles, carbamates).

[0084] Composition of the support base In one or more embodiments, the support layer 3 includes at least one layer of elastomeric material including at least one elastomer. The layer of elastomeric material may include at least one elastomer, rubber powder, and preferably at least one filler, preferably a mineral filler.

[0085] In one or more embodiments, the at least one elastomer may be selected from the group consisting of synthetic rubbers, such as styrene-butadiene rubber (SBR), ethylene-propylene-diene monomer (EPDM) rubber, natural rubber (NR), and mixtures thereof.

[0086] In one or more embodiments, the at least one elastomer may be included in the support layer composition in an amount of from 7 wt% to 50 wt%, preferably from 20 wt% to 35 wt% of the composition.

[0087] In one or more embodiments, the at least one elastomer may include styrene-butadiene rubber (SBR) in an amount of 5 wt% to 25 wt% of the composition, natural rubber (NR) preferably in an amount of 0 wt% to 10 wt% of the composition, and EPDM rubber preferably in an amount of 0 wt% to 10 wt% of the support layer composition.

[0088] In one or more embodiments, the composition contains at least one filler selected from the group consisting of organic fillers (wood flour, cellulose fibers) or other inorganic fillers (mainly talcum, calcium carbonate, silica, carbon black, kaolin, aluminum trioxide, magnesium dioxide), possibly bio-based fillers. The at least one filler is present in the composition in an amount ranging from 30 wt% to 200 wt%, preferably from 30 wt% to 100 wt%, based on the weight of the at least one elastomer.

[0089] In one or more embodiments, the rubber crumb is selected from pre-consumer or post-consumer halogen-free rubber manufacturing processes or shredded or devulcanized end-of-life tires (ELT) recovery processes, having a particle size of 50 μm to 4 mm, preferably 400 μm to 2 mm, and is present in the composition in a content of 30 wt % to 200 wt %, preferably 130 wt % to 180 wt %, based on the weight of the at least one elastomer.

[0090] In one or more embodiments, the described compositions comprise at least one pigment, inorganic or organic, selected, for example, from among the materials already indicated for the treading layer, present in the composition in a content of 0.3 wt% to 10 wt%, preferably 0.5 wt% to 7 wt%, relative to the weight of the formulation.

[0091] In one or more embodiments, at least one compatibilizer is present, which may be selected from the group consisting of silanes, preferably mercaptosilanes and / or vinylsilanes, hydrocarbon-derived resins and / or waxes (e.g., benzofuran resins, coumarone resins, aliphatic hydrocarbon resins, commonly known as C5 resins, C9 resins, or C5 / C9 resins), long-chain fatty acids, preferably stearic acid and oleic acid, and mixtures thereof.

[0092] In one or more embodiments, the composition of the support layer may include coumarone in an amount of 1 wt% to 3 wt%, preferably 1.5 wt% to 2.5 wt% of the composition.

[0093] In one or more embodiments, the composition of the backing layer may include a long chain fatty acid, preferably stearic acid, in an amount of 0.3 wt% to 2 wt%, preferably 1 wt% to 2 wt% of the composition.

[0094] In one or more embodiments, the support layer compositions described above may include chemical additives, also known as process aids, that are useful in industrial plants to control the viscosity and workability of the composition.

[0095] In one or more embodiments, the processing aid may be, for example, a plasticizing compound, which allows for adjustment of the viscosity of the composition and can adjust the glass transition temperature of the elastomer, which changes after the crosslinking process of the composition. The plasticizing compound may be selected from the group consisting of esters of phthalic acid, esters of phosphoric acid, adipates, sebacates, aliphatic and aromatic oils, antiozonants and dispersants, polyethylene glycol (PEG), esters of fatty acids, metal soaps (e.g., calcium stearate and zinc stearate), zinc and stearic oxides, reinforcing resins, and adhesion promoters or inhibitors.

[0096] The crosslinking step of both compositions used to obtain the two layers may be carried out by vulcanization using a sulfur process and accelerators, or by vulcanization using sulfur donors, or by crosslinking using peroxide crosslinking agents (such as dicumyl peroxide or tert-butyl peroxide), or by a combination of the three processes mentioned.

[0097] In one or more embodiments, the crosslinking accelerator may be selected from the group of, for example, CBS (cyclohexyl-benzothiazole sulfenamide, CAS No. 95-33-0), TMTD (tetramethylthiuram disulfide, CAS No. 137-26-8) or MTB (mercaptobenzothiazole, CAS No. 149-30-4), ZDBC (zinc dibutyldithiocarbamate, CAS No. 136-23-2), or other accelerators of the same series (sulfenamides, thiurams, thiazoles, carbamates).

[0098] The compositions used to prepare the support layer and the treading layer may be obtained using a mixer, in which at least one elastomer and rubber powder, and optionally at least one plasticizer, at least one filler are first mixed in one pass or in several successive passes, and optionally at least one reinforcing filler, chemical additives, and crosslinking additives are added.

[0099] In one or more embodiments, the resulting composition can be processed, eg, transformed into a layer to cover the flooring to be used, eg, using molding, extrusion, or calendaring.

[0100] In one or more embodiments, the compositions so treated can be crosslinked via a thermal process such as, for example, hot calendering or thermoforming, via other irradiation processes such as using a microwave source, infrared or electron beam, or via hot-air cross-linking.

[0101] The resulting floor covering can provide a slip resistance of 80 to 110 (dry) or (≥) 47 (wet) or higher according to EN 13036-4. The impact absorption according to EN 14808 can be 25% to 50%, preferably 35% to 50%. The vertical deformation can be 0.6 mm to 3 mm, preferably 1 mm to 2.5 mm. The abrasion value according to UNI EN ISO 5470-1 (H18 wheel, 1 kg / wheel, 1000 cycles) can be (≤) 4000 mg or less, preferably ≤ 3000 mg. The floor covering can have an ultimate tensile strength according to EN 12230 of ≥ 0.5 MPa, preferably ≥ 0.6 MPa. The relative elongation at break according to EN 12230 can be ≥ 100%, preferably ≥ 120%. The flooring material may have a hardness (Shore A hardness; UNI ISO 48-4) of 45 to 65 Shore A, preferably 50 to 63 Shore A.

[0102] Example Below are non-limiting examples of flooring according to aspects of the present disclosure.

[0103] The flooring material comprises a treading layer of thickness equal to 5 mm obtained using a mixture of NR / SBR / PDM elastomers with a content of 25-35 wt%, a mixture of mineral fillers (calcium carbonate, kaolin, silica) with a content of 30-100 wt% by weight of the elastomer, rubber powder with a content of 100-150 wt% by weight of the elastomer, and iron oxide pigments in an amount equal to 10 wt% of the layer. This layer is vulcanized by a sulfur crosslinking process in the presence of zinc oxide and a CBS accelerator.

[0104] The flooring material further comprises a support layer obtained by using a mixture of NR / SBR / PDM elastomers in an amount of 20-35 wt%, a mixture of mineral fillers (calcium carbonate, kaolin, silica) in an amount of 30-100 wt% based on the weight of the elastomer, and rubber powder in an amount of 130-180 wt% based on the weight of the elastomer, which is vulcanized by a sulfur crosslinking process in the presence of zinc oxide and a CBS accelerator.

[0105] The support layer has a thickness of 9 mm and includes a first array of voids having an elliptical cross section with a major axis A of 14 mm and a minor axis B of 9 mm, and a second array of voids having an elliptical cross section with a first axis a of 6 mm and a second axis b of 5 mm. The depth of the voids is 6.5 mm.

[0106] FIG. 3 shows an embodiment of an impression cylinder used to obtain the voids in the support layer of the flooring described above.

[0107] Flooring characteristics Table 1 shows the properties of the flooring obtained with the parameters according to the example and is compared with a flooring obtained with the same formulation but with hexagonal voids. [Table 1]

[0108] A 3% increase in mass per unit area increases the tensile strength by 13%, but also increases the relative elongation at break by 7%. A parallel increase of 37% in tear strength is also noteworthy. Unexpectedly, the increase in mass per unit area is accompanied by a significant 3% increase in FR value.

[0109] Verification of flooring properties The properties of the flooring materials described above were investigated in more detail using detailed FEM models of the materials that make up the products, and using an FR measurement device as shown in Figure 4. In Figure 4, the left side shows the structure of the FFM model of the Berlin Artificial Athlete (AA), the FR measurement device (EN 14808), installed on an athletics track, and the right side shows an example of the flooring material used in the tests described below.

[0110] The FFM model was applied to evaluate FR values ​​using various specific formulations of viscoelastic materials to identify those exhibiting better performance in the space of structural parameters representing industrially applicable solutions for athletics tracks. The model was validated by generating some of the most interesting solutions, where the mechanical properties were measured.

[0111] In particular, the tests carried out confirmed that the use of a specific formulation of the flooring layer, in combination with the specific structural properties of the voids in the support layer, makes it possible to obtain an optimal elastic response of the flooring even in the presence of slight dimensional changes in the voids, and that the correct selection of the degree of voids in the support layer and the specific dimensional ratio of the void shape guarantees the achievement of high FR values ​​associated with excellent mechanical properties.

[0112] Figure 5 shows the results of the simulations carried out, evaluating the effect of the void volume on the FR value of flooring materials with different structures but the same overall thickness. These simulations made it possible to confirm, in a totally unexpected way, that in addition to the known proportional relationship between the FR value and the void volume, there exist structural (or geometric) solutions, which turned out to be considerable, with FR differences in the range of 3-5% for the same void volume.

[0113] Additionally, further simulations were performed to understand the effect of void depth, especially whether this parameter is general compared to other structural features. Again, in this case, the results were surprising, since void depth is not general in terms of other structural variations, even though a proportional relationship between void depth and FR value was confirmed, as shown in Figure 6. Indeed, while it is true that larger void depths generally lead to higher FR values, it is also true that within the framework of comparable depth values, it is possible to identify solutions with different structures that can achieve significantly higher variations in FR.

[0114] Following further detailed analysis, structures with elliptical void cross-sections were simulated by performing a series of experiments to examine the effect of structural changes on FR values, as shown in Figure 7. This series of experiments yielded interesting and unexpected results compared to similar results obtained from hexagonal-based voids. Experiments with elliptical void cross-sections confirmed the trend pattern of results for hexagonal geometries, but highlighted a much narrower distribution of results (i.e., reduced variance) for the same void volume, despite preserving the possibility of selecting different FRs.

[0115] By overlaying the results, as shown in Figure 8, another surprising and unexpected aspect can be confirmed: given the same volume of voids, oval void shapes can generally achieve higher FR values ​​than voids with hexagonal shapes.

[0116] In a more detailed study, the effects of changing two structural parameters (width and height) were examined for elliptical and hexagonal shapes, while the void depth and floor thickness were kept constant. The results obtained were particularly unexpected and surprising. As shown in Figure 9, in the case of hexagonal voids, small dimensional changes significantly affected the FR value, while this was not observed for voids with elliptical cross sections, which instead showed a fairly regular change in FR value as the void dimensions changed. Under the same structural conditions, the higher FR value of flooring with voids having elliptical cross sections was further confirmed compared to flooring with voids having hexagonal cross sections.

[0117] The above results have particularly important consequences from an application point of view: in the production of technical articles made of rubber, there are dimensional tolerances in production that may result in the acceptance of articles that are apparently similar to one another, but in practical applications, this may result in differences in FR values ​​that have been difficult to account for up to now. Similarly, the process of placing these materials requires the use of adhesives, which may possibly fill voids, and thus the FR value of the material may change, sometimes in unpredictable ways.

[0118] The use of voids with an elliptical cross section using the elastomer mixtures used in the simulations of the present invention ensures the possibility of selecting FR values ​​in a way that is partially independent of the porosity (i.e. the volume of the voids) and therefore of selecting mechanical properties for flooring that are particularly suitable, such as, for example, good resistance to spikes in athletic shoes.

[0119] The invention makes it possible in particular to obtain flooring with constant FR values ​​and homogeneous behavior, regardless of the conditions of production or installation, thereby characterizing new-generation sports surfaces that are highly effective and superior to those of the past.

[0120] In particular, the floor covering described above in this application has the following advantages: High uniformity of elastic response (optimal constancy of FR values ​​despite changing conditions of manufacture and installation, which may lead to changes in the dimensions and shape of the support layer grid); Higher FR values ​​even under lower porosity values ​​than existing solutions, or in other words, higher FR values ​​for the same porosity; Considerable freedom in the selection of the mechanical properties of the final product: once the FR value has been selected, the choice of the structural parameters of the surface allows to select combinations that make it possible to obtain optimal mechanical properties of the surface in different situations of use (training, competition, with shoes with different spikes).

Claims

1. a treading layer (2) comprising at least one layer of elastomeric material; and a support layer (3) comprising at least one layer of elastomeric material; A sports flooring (1) comprising: A sports flooring (1) in which the support layer (3) comprises a first array of voids having an elliptical cross section (5).

2. A sports flooring (1) according to claim 1, The support layer (3) comprises a first array of voids having an elliptical cross section (5); A sports flooring (1) having an elliptical cross section with its major axis (A) oriented in the longitudinal direction (Z) of the flooring.

3. A sports flooring (1) according to claim 1 or 2, the support layer (3) comprises a second array of voids having an elliptical cross section (5a); A sports flooring (1) in which the elliptical cross section (5a) has a first axis (a) and a second axis (b) that are perpendicular to and coplanar with the major axis (A) of the elliptical cross section of the voids of the first array of voids.

4. A sports flooring (1) according to claim 3, The sports flooring (1), wherein the first axis (a) and the second axis (b) have the same length.

5. A sports flooring (1) according to claim 3 or 4, A sports flooring (1), wherein said first axis (a) and said second axis (b) have a length that is shorter than a major axis (A) of the elliptical cross section of the voids (5) of the first array of voids.

6. A sports flooring (1) according to any one of claims 1 to 5, Each cavity (5a) has an elliptical cross section, A sports flooring (1) in which the ratio of the length of the first axis (a) to the length of the second axis (b) is between 1 and 2, preferably between 1 and 1.

2.

7. A sports flooring (1) according to any one of claims 1 to 6, The sports flooring (1) comprises a support layer (3) comprising a first array of voids having an elliptical cross section (5), the elliptical cross section having a major axis (A) of 6 mm to 18 mm, preferably 9 mm to 15 mm, more preferably 11 mm to 15 mm.

8. A sports flooring (1) according to any one of claims 1 to 7, The sports flooring (1) comprises a support layer (3) comprising a first array of voids having an elliptical cross section (5), the elliptical cross section having a minor axis (B) of 6 mm to 12 mm, preferably 6 mm to 10 mm, more preferably 7 mm to 10 mm.

9. A sports flooring (1) according to any one of claims 1 to 8, the support layer (3) comprises a second array of voids having an elliptical cross section (5a); The sports flooring (1) wherein the second arrangement has a first axis (a) of between 0 mm and 8 mm, preferably between 2 mm and 6 mm, more preferably between 3 mm and 5 mm.

10. A sports flooring (1) according to any one of claims 1 to 9, the support layer (3) comprises a second array of voids having an elliptical cross section (5a); The sports flooring (1), wherein the second arrangement has a second axis (b) of between 0 mm and 8 mm, preferably between 2 mm and 6 mm, more preferably between 3 mm and 5 mm.

11. A sports flooring (1) according to any one of claims 1 to 10, the distance (C) between the centers of two consecutive voids of the first array of voids (5) is between 12 mm and 32 mm, preferably between 12 mm and 27 mm, more preferably between 14 mm and 26 mm; The sports flooring (1), wherein said distance (C) is oriented in the longitudinal direction (Z) of the track.

12. A sports flooring (1) according to any one of claims 1 to 11, the distance (D) between the centers of two consecutive voids of the first array of voids (5) is between 12 mm and 32 mm, preferably between 15 mm and 24 mm, more preferably between 17 mm and 21 mm; The distance (D) is oriented perpendicular to the longitudinal direction (Z) of the flooring (1).

13. A sports flooring (1) according to any one of claims 1 to 12, The sports flooring (1) wherein the support layer (3) has a thickness of 3 mm to 15 mm, preferably 6.5 mm to 10 mm.

14. A sports flooring (1) according to any one of claims 1 to 13, The sports flooring (1) wherein the treading layer (2) has a thickness of 3 mm to 9 mm, preferably 4 mm to 8 mm, more preferably 5 mm to 7.5 mm.

15. A sports track, in particular a running track, equipped with a flooring (1) according to any one of claims 1 to 14.

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